Automatic fluid pressure transmission



July 22, 1952 w. 1'. LIVERMORE 2,604,197

AUTOMATIC FLUID PRESSURE TRANSMISSION Filed Aug. 50, 1946 5 Sheets-Sheetl INVENTOR.

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AUTOMATIC FLUID PRESSURE TRANSMISSION Filed Aug. 1946 5 Sheets-Sheet 5IN VEN TOR.

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Patented July 22, 1952 AUTOMATIC FLUID PRESSURE TRANSMISSION I '1LivermoreyGro'sse Pointe,-1\Iicli. I Application August 30, 1946, SerialNO. 693 874 1 This invention relates to" aiitomatic; fluid' pressuretransmissions of the samegeneraitype? as disclosed in my priorU'nitedStatesLettersPatent No. 2;120,104 granted June; '7, 1938, and" No.2,376,545"granted" May'2'2, 1945", and has for its principal object toincorporate in such atransmission several important-improvements wherebythe flexibilityand adaptability of such a transmission to manydifierent'conditionsis materially enhanced; whereby marked" improvementsin smoothness" of operation are obtained; whereby changes from one gearratio to a different gear ratio are. effected without objectionablejerking effects and'whereby the "various control valves that formcomponent parts of the iiuidi pressure control system are caused to beoperated with smoothness and precision without requiring undue effort orpower to be applied. to cause a proper functioning of suchzvalves.

In addition to the above broader aspects of the present invention, ithas among other objects the following;

One object of the invention is" to provide an improved automatictransmission with four forward gear ratios which may" be progressivelyengaged by the progressive application of two friction clutches and" theshifting'of" a synchronizer unit from one position to another;

Another object is' to provide improvedfluid pressure means for actuatingthe. clutches and for shifting the synchronizer'unit." I A furthenobjectis to provide an improved fluid pressure'control' system responsive toen'- gine speed, throttle position and? vehicle speed for controllingsuch actuating fluid pressure means.

Another object is to provide improvediexpanding diaphragm means forcausing engagement of the friction clutches which will effect: a clutchengagement pressure proportional to the fluid pressure within suchdiaphragms:

A further object is to provide for the engagement-of the first gearclutch with the pressure of engagement being responsive to the combinedinfluence-of engine speed and throttle position.

Another object is to provide automatic means for engaging second, thirdand; fourth geardrives responsive to vehicle speed and throttleposih'on.

A further object is to'provide automatic means for shifting directlyfrom second'to fourth gear during normal acceleration of" the vehiclebut with means controlled by the accelerator for causing shiftsprogressively through first, second,

acceleration is desired.

' r16 claims. (01. 192-.0'73) Another object is to provide automaticmeans controlled by the accelerator for causing, down shifts from fourthto third gear drive Where rapid acceleration, is desiredwhen the,vehicle is in fourth gear drive. Y

A further object is to provide automatic means for causing progressivedown shifts from fourth to third to second and. to firstj gearwhererequired as in ascending a steep hill upon which the vehiclecontinuously. slows down.

Another object is to provide means for free wheeling uponreleasing theaccelerator while the vehicle is in first, or second gear'drive butproviding means for thev engine to .act' as a brake when the acceleratoris'ireleased while the vehicle is traveling'in third or. fourthgeardrive.

A further objectisto provide means manually operable by the driver forshifting from fourth to second gear drive under conditions" whereextreme acceleration is desired; v

Another object is to provide" means manually operable by the driver forholdingthe'vehicle in second gear drive and preventing operation of theautomatic shift third and fourth gear drives:

A- further object isto provide means manually operable by the driver to'permit the vehicle to drive the engine, or to permit the engine to actas abrake with the vehicle in" second; gear drive wheresuch is desiredas for starting theicar; by towing or pushing'or'as in" descendingaste'ep' hill.

Another object isto provide'automaticl means for complete release ofdriving engagement when the vehicle is brought'to a stop as. at'alsto'pilight by merely releasing the accelerator and for reengaging'the'driving. means when it is desired to again start the vehicleibythe-mere depression of the accelerator thus avoiding any undesirablecreeping engagement when the-vehicleis brought to a stop as well as anynecessity for manual I clutch release or gear shift, I v v A furtherobjectis toprovide a fluid pressure means. and a fluid pressure controlsystemfor meeting each of the aboveautomatic requirement&

Another object is to provide engine driven means for normally 1maintaining; asupphz; offluid under pressure as well. as, an auxiliary;means for supplying such; fluid pressure-in the-event it maybe necessaryto starttheengineqthrough towing or pushing.

A further object is to'provide automatiemeans for causing up shifts in.response; to increased vehicle speed and to provide means controlled bythe accelerator for causing such up shifts to occur at higher vehiclespeeds in response to increased depression of accelerator and opening ofthrottle.

Another object is to provide fixed limit means for causing up shifts atpredetermined maximum throttle openings regardless of throttle openingsabove such predetermined maximum points.

A further object is to provide automatic means for causing down shiftsin response to decreased vehicle speed and to provide means controlledby the accelerator for causing such down shifts to occur at highervehicle speeds in response to increased depression of accelerator andopening of throttle.

Another object is to provide fixed limit means for causing down shiftsat predetermined minimum throttle openings regardless of throttleopenings below such minimum points.

A further object is to provide automaticmeans v fourth or third tosecond .gear drive at vehicle speeds above such maximum;

Another object is to provide a main pressure control valve' forregulating the pressure available to actuate both of the clutches, suchvalve being responsive to'accelerator or throttle position, and forcausing such pressure to be proportional to the extent'of acceleratordepression.

A further object is to provide centrifugal means responsivelto' enginespeed and associated with the first gear clutch fluid'p'ressure meansfor causing such'pressure to beproportional to engine speed.

Another object is to provide cam means actuated by the accelerator forin turn actuating the throttle, the main pressure control valve and thedifferential means mentioned above for influencing the vehiclejspeedi atwhich up shifts and down shifts will occur. I l r A further object is toprovide a clutch valve .for regulating the flow of fluid from the mainpressure control valve to the fluid pressure means for actuating thesecond gear clutch.

Another object is to provide throttling means for causing such fluid togradually and smoothly actuate such second gear clutch. I V

A further object is to provide a clutch pilot piston for controlling themovement of such clutch valve to open and closed positions and meansresponsive to vehicle speed and accelerator position for actuating suchclutch pilot valve.

Another object is to'providespring means for urging the synchronizerunit into a position for A further object is to provide means forpreventing movement of the synchronizer valve to a position foradmitting or exhausting fluid pressure to shift the synchronizer unitwhile the first and second gear clutches are engaged.

Another object is to provide automatic means responsive to movement ofthe synchronizer pilot piston for releasing first and second gearclutches and closing the throttle prior to shifting of the synchronizerunit from one position to another.

A further object is to provide means for rapidly exhausting fluidpressure from each clutch actuating means prior to such shift of thesynchronizer unit.

Another object is to provide an interlock valve for controlling theactuation of such clutch release and throttle closing means.

A further object is to provide for flow of fluid through such interlockvalve to move the pressure control valveto exhaust position forreleasing pressure from theclutoh actuating means and for'flow of fluidto the throttleclosing means when the synchronizer pilot'valve is movedto a position for causing the synchronizer unit to shift.

Another object is to provide means for permitting the synchro valve tomove from one position to another when the fluid pressure for actuatingthe clutches has been released.

A further object is to provide a means for bypassing the throttlingmeansefiective to produce gradual application of the second gear clutch,to permit rapid discharge offluid from the second gear clutch actuatingmeans for .the release of such clutch. p

Another object is to provide-release control means for effecting rapidinitial release and gradual final release of fluid pressure foractuating the second gear clutch when the first gear clutch remains,engaged and the drive is to be transferred from the second gear clutchto the first gear clutch as in effecting down shifts from fourth geardrive to third gear drive or from second g'ear'drive to first geardrive.

A further object is to provide a timing valve for assuring the propertimed relationship between the release of the clutches and the closingof the throttle prior to shifting of the synchrom'zer unit.

Another object is to provide means responsive to movement of thesynchronizer unit for shifting the position of the interlock valve andfluid pressure means controlled by the interlock valve in such shiftedposition for causing re-engagement of the clutches and for releasing thethrottle closing means.

A further object is to provide automatic means for causing a relativelyfast closing of the throttle and a relatively slow re-opening of thethrottle before and after shifting of the synchronizer unit.

Another object is toprovides means for preventing the automatic closingof the throttle to register an impulse back to theaccelerator.

The above and other objects of the present invention will appear morefully from-the following more detailed description and by reference tothe accompanying drawings forming a part hereof and wherein: V

Fig. 1 is a longitudinal vertical section through a transmission gearcasing or housing, the various gear clutches and other associated partsbeing shown in cross section therein;

' Fig. 2 is a diagrammaticv view of the various valves and fluid:pressure mechanism, showing theconnecting conduits between such valvesand the various'levers and connecting links which are associated withsuch valves to complete the fully automatic transmission control; I

3 is a cross sectionaldetail taken on line 3-3 of Fig. 1; I I I Fig. 4is an enlarged view through the governor operated pilot valve for thesecond and fourth gearshift; I I I Fig. 5 is an enlarged longitudinalcrosssection through the synchronizer collar and one of the associatedgears, showing the details of a form of free wheel unlocking device forfacilitating disengagement of thegear teethof thesynchronizer unit fromthe jaw clutch teethpfthe associated gear; I

Fig. 6 is a sectional detail of the cone 205, lug 206, slot 291 and hub208 taken in a plane perpendicular tothat ofFl'g. 5.

Fig. 7 is a sectional detail on the line 1-1 of Fig. 5; I

Fig. 8 is a somewhat diagrammatic plan view of the teeth of thesynchronizer' collar, the blocking gear teeth on the synchronizer coneand the jaw clutch teeth on the driven gear with which the internal gearteeth of' the synchronizer collar are adapted to be engaged;

Fig. 9 is a longitudinal vertical section through a modifiedtransmission gear casing or housing, the various gear clutches and;otherassociated parts being shown in cross section therein; and I Fig.10 is a diagrammatic view of the various valves and fluid pressuremechanisms, showing the connecting conduits between such valves andthe-various levers and connecting links which are associated with suchvalves to complete the fully automatic modified transmission control forthe transmission proper shown in Fig. 9.

In Fig. 1 of the accompanying drawings, the transmission properconsisting of a plurality of clutches, fluid pressure clutch operatingdevices, transmission gears and control governor; are mounted in acomposite gear casing or housing. This housing consists of a number ofseparate parts suitably bolted together to form a single integralunitary structure divided into three main compartments, indicated by thereference characters A, B and C. Compartment A which consists of twoseparate castings A and A bolted together encloses aplurality of fluidpressure actuated clutches together with the fluid pressure devices foractuating said clutches. Compartment 3 contains all of the transmissiongears, while compartment C houses a speed governor.

As shown in Fig. lof the drawings, and as will be more fullyhereinafterdescribed, the present automatic transmission consistsessentially of a four-speed gear set which includes a shiftable orsliding transmission gear synchronizer hav ing the usual characteristicsof such a device together with spring means normally urging suchsynchronizerinto an inoperative neutral position and fluid pressureoperating means to shift such synchronizer from a neutral position to anoperative gear connectingposition, two main clutches together withmeansfor causingautomatic engagement of one of said clutches by hydraulicmeans and the other under a combination of hydraulic and centrifugalcontrol means; a centrifugal governor connected with the driven oroutput shaft of the transmission gear set to be responsive to variationsin vehicle speed; a pair of pumps for supplying fluid under pressure-t0I Referringto Fig. 1 of the drawings, the numeral Iii-indicates aflywheel or other member driven from the engine of an automotivevehicle. Driven selectively from such flywheel, by means more fullyto bedescribed, are-a pair of clutches- H and I2, driven elements of whichare keyed, respece tively, to the shaft l'3-and a sleeve [4.

. Low speed or first gear driveis effected byengagement of clutch [2through the sleevel4' and apinion gear I5, preferably formed integralwith the sleeve, and which pinion ['5 meshes with a gear l6 mounted atone end of a countershaft sleeve IT by means of a freewheeling unit oroverrunning clutch Iii-a. Suitably splined or otherwise secured on theother end of the countershaft sleeve I1 is a sliding gear pinion I8adapted to mesh with a gear l9whichis connected by means of anoverrunning clutch 26 to the driven or output shaft 2! of thetransmission proper.

Second gear is obtained by engagement of the clutch Ii, transmittingdrive through the shaft it which has preferably formed'integrallytherewith a driving pinion 22. Drive pinion- 22 meshes with a secondgear 23 keyed upon the countermovement thereon by a snap ring 23-0,; thedrive then being transmitted through countershaft sleeve il and gearslB- and I9 tothe driven or output shaft 2|. At this point, it maybenoted that after low gear hasbeen established through engagement of theclutch [2, second gear may be effected through engagement of the clutchll without necessitating the disengagement of clutch l2, because whensecond gear is effected through the gears 22, 23, the rotation of thecountershaft sleeve at the higher speed ratio obtained through gears 22and 23 will merely cause the free wheeling unit Hi -a to becomeautomatically disengaged, thus permitting the countershaft sleeve I! toturn fasterthan the gear i6.

The countershaft sleeve H is rotatably mounted upon a, stationary shaftI l-a'which is non-rotatablysecured in the end wall portions of' thegear casing compartment B, suitable bearings I'I-b being interposedbetween the sleeve H and shaft ll-wand the shaft being providedwith alongitudinally extending central bore Il -c which serves as an oilconduit having radial branches l'l-d through which oil is admitted'forlubricating the said'bearings.

Aswill be seen from Fig. 1, the output or driven shaft 2i'ofthe-transmission is piloted-within a counterbore'formed in the enlargedgear end of the input shaft l 3, an anti-friction roller bearing 24-being provided between the reduced end of the output shaft andthecounterbore of theinput shaft. Suitably splined upon'output shaft 2!is the=inner collar or hub 25 of a'synchronizer unit which includes theusual cone-shaped friction clutch members 26, 21, the inner faces ofwhich engage cone-shaped extensions-26-a and 21-11 on the gears l9 and22, respectively; the friction cone collars 26 and 21 being interposedbetween the said extensions and the sliding collar 28v of thesynchronizer unit. Each of the cone collars 26,

21am provided with the usual blocking gear teeth 26-band 2|b,,commonlyemployed in the modern type of synchronizing gear units; Collar 231sprovided with internal gear teeth 28,-ia'adapted to be engaged with thegear teeth IS-a and 22-a formed integral with the gears l9 and 22,respectively. 1 1 c As will be obvious from the foregoing descrip: tion,when the collar 28 is slid-to the right in Fig. 1 to engage with thegear teeth |9- a, the gear |9will be locked in driving engagement withthe output shaft 2|, while, when the synchronizer collar 28 is slid tothe left to engage the internal gear teeth 28-a thereof with the gearteeth 22-a of gear 22 on the end of driving shaft l3, the shaft |3 willbe locked in direct drive relationship with the output shaft2| r Theforegoing gear arrangement is adapted to shift directly from second gearto the direct gear driving relationship just described, which, in thepresent constructional example, is a fourth gear drive. The direct shiftfrom second to fourth gear drive requiresthat the driving shaft l3,which during second gear drive rotates at a faster speed than the outputshaft 2|, be sloweddown to a synchronous speed before the synchronizercollar 28 can be shifted to the left. Such slowing down in turn requiresthat the engine be slowed down or that clutch I I be momentarilyreleased, or that both such conditions be efiected. With the controlsystem hereinafter described, both clutches are released and thethrottle is closed reducing the engine speed prior to shifting of thesynchronizer collar 28, after which both clutches are re-engaged and thethrottle opening restored to effect the direct drive relationship betwenthe driving shaft I3 and the output shaft 2|. When this drivingconnection is thus effected, it is to be noted that shaft 2| will beturning faster than gear I9 which is still being driven through gears22, 23 and [8 through shaft l3 and clutch H and that, therefore, rollerclutch 20 will be in overrunning condition. The same is likewise truewith respect to roller clutch IG-a, as the countershaft sleeve will alsobe driven faster through gears 22 and 23 than gear I6 is driven bypinion gear IS.

A third gear ratio suitable for acceleration at high speed, such asdesired for passing another car, or ascending a steep grade, isalso'provided intermediate between second gear drive and'direct drive.This gear ratio is obtained by releasing clutch member II when thevehicle is in direct drive through the actuation of the automaticcontrol means, later to be described, and the drive is thenautomatically transferred to clutch member l2 which is always inengagement whenever driving in either direct drive or third gear, and istransmitted through sleeve i4, gears l5, l6, roller clutch IG-a andgears 23, 22, jaw gear teeth 22-a of the latter to the synchronizercollar 28 and thence to the output shaft 2 I. This is usuallyaccomplished by the driver depressing the accelerator pedal beyond thepre-determined position, as will belater more fully described, whiledriving the car in fourth'or' direct drive gear.

There are times when it is necessary or desirable to use the engine as abrake in secondgear when descending a very long steep grade; The secondgear described above is not suitable for this purpose, as the drivepasses through the free wheeling .unit or overrunning clutch 20 providedbetween the gear I 9 and the output shaft2l, which overrunning clutch,while adapted to transmit a drive from gear l9 to output shaft 2|, isnot adapted .to transmit the drivein the reverse order, that is from theoutput shaftbackthrough gear I9 tothe engine. As it is necessary. whenusing the engine as a brake for the drive to be transmitted from theoutput shaft back through the transmission gearing to-the engine, theuse of the engine as a brake in the present construction is effected bymoving the synchronizercollar28 to the right to cause the internal gearteeth 28-a thereof to engage with the jaw teeth, |9 -a of gear l9. Whenthis connectionis effected, rotation of the output shaft is communicatedthrough the synchronizer unit directly to the gear l9 and thence to gearI 8, countershaft sleeve I 1, gears 23, 22 and driving shaft |3to clutchH and thence to the'engine. If the car is being driven'in directdrive,the synchronizer collar 28 will be turning at the same speed as theengine, whereas, thegear l9 and its jaw teeth I9-a will be driven at aslower speed through the gears 22, 23 and I8. Therefore,in order toengage the synchronizer collar 28 with the jaw teeth I 9-a, it is'necessary to momentarily disengage the clutch so that the friction cone26 associated with the gear l9 will be able to speed up the latter untilthe jaw teeth IS-a thereof are rotating at the same speed as the collar28; the internal gear teeth 28 -a of the collar 28 can then be readilyslid into mesh with the jaw teeth I s-a of the gear I9. 7 d

When an overrunning clutch, such as the clutch 20, is employed, therewill be a tendency for the clutch to jam and lock the rollers inengagement if drive is transmitted backwardly to the engine from shaft2| by the motion of the vehicle. This is due to a slight twisting orwinding up of the shaft, thereby causing the rollers of the overrunningclutch 20 to be held in locked engagement by the torque pressure betweenthe internal gear teeth 28-a of the synchronizer collar 28 and the jawteeth Iii- When the drive is released, the locking effect between theoverrunning rollers and the torque pressure of the gear teeth 28-a andLa frequently is so great that it becomes impossible to disengage thesynchronizer collar 28 from the jaw teeth |9-a bymeans of the manualshift lever provided for this purpose. To prevent this from happening,the'splines 2|-a (Fig. 3) by means of which the cam member 20a of theroller clutch 20 is keyed to the output shaft 2| are made with a .loosefit or back-lash clearance in the spline keyways of the cam member 2041,and a torsional spring 204) (Fig. l) is interposed between the,

shaft 2| and the cam member 20-a which, when the load is removed, willpermit a slight amount of relative rotational movement between the saidshaft and the cam member sufficient to release the jamming or lookingengagement of the rollers.

As shown in Fig. 5, the rollers 200 of the free wheeling roller clutchare rotatably mounted in a roller cage 20| between which, and the hub orcollar-202 of the roller clutch which is splined to shaft 2|, isinterposed a torsional spring 203 arranged to normally urge the cage20l-in a counterclockwise direction (Fig. 7) to cause the rollers totravel upthe cam surfaces 204 towards locking position. As shown inFigs. 5 and 6, the friction cone 205 is made integral with or attachedto the roller cage 20| and is provided with a small projectingrectangular lug 206, also shown in Figs. 6 and 8, which extends into aslot201 provided in the hub member 208 of the synchronizer'unit, therebeing a clearance between the lug 206 and the slot 201 slightly lessthan the spacing of the internal gear teeth 209 of the synchronizercollar 2). The engagement of the lug 206 with the slot 201 serves tolimit the amount of-angular swing of the cone ings, in which positionthe roller's'are moved towards locking position tojeffect drive throughthe overrunning roller clutch by the rotation of gear I9. When the cage20! is in such a position relative to the cam surfaces 204 as to effectdrive in this manner, theipositio'n of the blocking teeth "2H of thecone2il5 relative to the internal gear teeth .209 of the synchronizercollar is a blocking position, and before the synchronizer collar. 2H!may beshifted to the right to engage the jaw teeth 212, it isn'ecessarythat the cone 205 and cage '20] be rotated in a clockwise direction, asshown in Fig. '7, a distance relative to the hub ine'mb'er'ZGB andcollar 2"] sufficient to move the blocking teeth into engaging alignmentwith the gear teeth 28% as shown in Fig. 8.. Such rotation 'will alsoeffect a clockwise rotation of the cage 2M relative to the cam surrceszon against the action of the torsional spring 203 sufficient todisengage the rollers 2530 from their drive transmitting position. Suchrotation'of the cone 285 and cage 201 against the torsional spring 203may be produced manually by' urgin'g v the synchronizer collar 2m to theright since the side edges of teeth 2'09 and 2H are chamfered so thatendwise movement of the collar will ,cause'such rotation, If the manualshift of the synchronizer collar 2 H] to the right is initiated whilethe output shaft is rotating at a faster angular velocity than gear [9,as when such shift is made from fourth or third gear drive, suchrelative rotation of the blocking teeth 2H to a non-blocking positidnand of the cage :20] to a disengaging position will be assisted by theoverrunning clutch action described above.

As will be seen from the foregoing description, the arrangement shown inFigs. to 8 inclusive, where the rollers of the overrunning clutch are'mounted in a cage made to rotate as a unit with the friction conemembers of the synchronizer in a manner whereby the engagement of thesynchronizer collar with the blockin'g teeth of the friction cone isaccompanied by disengagement or unlocking of the rollers, and with theprovision of the torsional spring to normally urge the rollers intoengaging or locking position, accomplishes the two-fold purpose ofnormally holding the rollers in a position where forward drive may betransmitted through them and of moving such rollers to an inoperativepositionwhen the output shaft is geared through the synohroni'zer unitto the engine for positive reversible second gear drive.

Reverse gear drive is obtained by sliding the gear H! to the left uponthe splines of the countershaf t sleeve 'ii until its teeth are broughtinto meshing engagement with the teeth of gear 30, gear 30 being madeas-a cluster gear integral with gear 34 'rotatablyinounted uponthe'fixed shaft 32: For simplicity of illustration, the gears 38, 31 areshown with their axisof rotation in the plane of the paper, whereas, inthe actual construction, the axis of "rotation of these two gears issuch that gear 3l' meshes withjgear 19. In ordertoe'stablish'reverse.drive, clutch 12 is engaged which transmits the drivethrough sleeve l4, gears I5 and I6 .to-the countershaft sleeve H andthence through gears I8, 39 and 3! to gear l9, and thence from jaw teethl9-a to the synchronizer collar ,28 to the output shaft 2].

It is to be noted that it is necessary for the 1-0 synchronizercollar28ftoj be engaged with teeth l9a of gear I9 as reverse jdrive;;coul'dnot be transmitted through the overrunning clutch '20. It will also benoted that, if gearf lB is slid ,tOJ the left from the position shown inl'to become disengaged from gear 19 withoutfeng'aging gear 38, a neutralcondition is obtained.

From the foregoing, it will t [seen that with the transmission of I thepresent invention, manual shifting means are re'quired for forwarddrive, neutral and reverse drive and also for a locked up or positivesecond gear drive through which the engine can be used as a brake, I J IIn normal operation the car is started automatically by the centrifugalengagement .of clutch [2, as the engine is speededuprwhile the shiftfrom first to second is accomplished, automaticallyiby hydraulicengagement of clutch If, as will presently be more fully described. Theshift from second to fourth may be semi-automatic, this beingaccomplished by releasing the accelerator pedal until, the engine slowsdown suiuciently forthe synchroniz'er collar '28 to be engagedautomatically with the Jaw teeth 22,-a of gear 22. This shift may,however, be 'made entirely automatic byproviding mechanism for closingthe throttle automatically when the proper car speed has been reachedandreopening the throttle after, the shift isycompleted; Ai

quicker shift'canbe madeif the clutchesv are released during the "shift;The shift can 'jth'en be completedas soon as the aption'Ofjthejsynchronizer brings jjaw, 'teeth'ZZ-w to the same speed as collar28without'jwaitihg for the engine to slow down. fIThe';downshif t;fromfourth to third is semiautomatic and occurs 'wh'c'nthe acceleratorpedalis depressed to a certainpoint, if the car istraveling at anappropriate speed. The downshift into second gear is also madeautomatically by disengaging the s'ynchronizer collar 28 from the jawteeth 22-h and'the shift from second to first is 'm'ade automatically byrelease of theclutch I 1,. All ofthe automatic I control meansfor;accomplishingthe'fabove functions will be hereinafter more fullydescribed. I

Centrifugal clutch I The means for effectingthe automatic kenga ement ofthe clutch 12 by centrifugal means as the car is speeded up in startingcomprisesi the following; I I I I I In addition tothe clutches proper Hand. 12, the clutch assembly" also includes central driving plate 33which is supported from and driven by the flywheel vlfLthrojigh aplurality of steel straps 34, the outer ehdsof which are bolted to theflywheel by bolts 35 and the inner ends of which {are bolted to thedriving plate 33 by means ofbolts 35. -'Movabl'epressure plates 37, '33are mounted,- respectively, adjacent to the "clutches! rand-42am aresupported from the-central driving plate 33, each by'thre'e' steelstraps similar to the st aps 34 and bolt's' 35, but which are not shownin the 'dr'awing because they are spaced at different points about theperiphery ofithe oentralnriving plate, the support of the plates' 31 and38'being such that, although the plates; 31,438. are held concentricwith the axis of rotatibn ofz the flywheel, they .are free to be ,movedlongitudinally to. apply pressureto the V, driven clutch members H andl2 by the, clutch igactuating means now to; be described: a. 1 1 Theclutchcover 40 is supported;-as a unit with e ce r ldrivinez t .3 by man o 11. rotates at all. times with the central driving plate 33whenever the engine is running. Said clutch cover in turn carrieswith'it a cylinder housing 4| which is piloted upon the driving sleeve Hby means of bushings 42, 43; sleeve I4 being in turn supported near itsright hand end by a ball bearing-44. It will be seen from the abovedescribed construction that the central driving plate 33, the clutchcover 46, the cylinder housing 4| and driving sleeve |4 thus form asingle unitary assembly which is connected at one end to the flywheel I6through the steel straps 34 and is, supported near its other end by theball bearing 44. l

Mounted in suitable cylinders formed in the cylinder housing 4|are'three slidable pistons 45 for actuatingthe clutch l2 and threesimilar pistons 46 for actuating clutch As clearly shown in Fig. l, thecylinder housing 4| has a reduced hub extension 41 and is provided withannular grooves 48, 49, which serve as collector grooves for fluid underpressure to be delivered to the pistons 45, 46, the grooves 48, 49 beingseparated by piston rings 50. The reduced hub 41 of the cylinder housingis rotatably mounted withinra stationary housing formed integral withcasting A and which is provided with conduits or ducts 52, 53' whichcommunicate, respectively, with the annular grooves 48, 49. Groove 49,communicates through a longitudinally extending groove 54 with thepistons 46, while groove 48 communicates through longitudinal groove 55with the pistons 45.

If clutch His to be engaged, oil is transmitted through duct 52 togroove 49 and thence through longitudinal passage 54 to pistons 46. Theoil pressure building up on the right hand end of pistons 46 istransmitted through cushion springs 56 to piston rods 51 to the innerends of levers 58 to the bolts 59 which serve as tension members, thelevers 58 pivoting in suitable apertures 60 provided in the clutch cover46, and causing the clutch pressure plate 31 to be pulled to the rightby the bolts 59 to clamp the members of clutch between the centraldriving plate 33 and the clutch pressure plate 31.

If clutch 2 is to be engaged, oil is transmitted through the duct 53,groove 48, longitudinal passage 55 to the pistons 45, and, as the oilpressure builds up behind pistons 45, the pistons are moved to the leftand the piston rods 6| exert pressure upon the inner ends of the levers62, causing said levers to be moved upon their fulcrumed pivotalengagement, like the levers 58, in suitable openings 63 provided in alever 64 and through which openings the outer ends of the levers 62project. As the piston rods 6|, and levers 62 are moved towards theleft, as above described, this movement is communicated to the pressureplate 33 through the pivotally mounted strut or push rods 65. The partsare so constructed that the stroke imparted to pistons 45 by the oilpressure is limited and does not impart to the right hand pressure plate38 a suflicient amount of motion to cause said plate to produce drivingengagement of the clutch member.

Initial engagement of the'clutch member' l2 in cooperation with themovement of the levers 62 by the pistons 45 is produced by means ofcentrifugal weights 66 which are mounted upon the left hand ends oflevers 64. Secured to the right hand end of levers 64 by'means of rivets61 is one endof a flexible steel strip 68, the other end of which issecured by a row of rivets 69 to a flat portion of the clutch cover. 48.The side of lever 64 adjacent to the steel strip 68 is arcuate in formsothat, as the weights 65 move outwardly under the influence ofcentrifugal force, the arcuate surface of the lever rolls upon theflexible strip 68 and causes said strip to be rolled up on the arcuatesurface of the lever 64 after the fashion of a belt upon a pulley or awindow shade upon a curtain rod. This movement obviously will cause theouter end of lever 62 to be moved toward the left and this motiontogether with that imparted to said lever by the hydraulic pistons 45'is sufiicient to move the clutch'pressure plate 38 an amount sufficientto produce driving engagement of the clutch l2. The parts are sodimensioned and adjusted that without the cooperation of the hydraulicpistons 45, the motion or action of the centrifugal means is notsufficient to produce engagementofclutch l2, and likewise the motion ofthe pistons 45,, as hereinbefore described, is in sufiicient to produceengagement of said clutch without the action of the'centrifugal means.

When the engine is stationary, release springs (not shown) of any commonor usual construction provided between the central clutch plate 33 andthe clutch pressure plate 38 hold the centrifugal weights and levers 66and 64 in their inward position, and against the periphery of the clutchpressure plate 31, which serves as a stop to limit the inwardmovement ofthe weights 66 to the position in which they are shown in Fig. 1 of thedrawing, and with the clutch i2 disengaged. These springs are of suchstrength that they permit the weights 66 to .move outwardly under theinfluence of centrifugal force until they contact against the inside ofthe rim of the flywheel H] in the dotted line position, shown in Fig. 1of the drawings, at theidling speed of the engine. The vehicle isstarted by admitting fluid under pressure to the pistons 45 and theengine is simultaneously speeded up by opening the throttle. As thecentrifugal weights are already held in the outer dotted line positionby the centrifugal force, the clutch I2 will be applied at a ratedepending upon the rate at which the oil flows to pistons 45. Thepressure on the clutch, however, will be limited by the amount ofcentrifugal forceexerted by the weights 66. If the engine is runningslowly and the centrifugal force on the weight is therefore light whenthe pistons 45 are caused to be moved to the end of their stroke by theoil pressure, the weights 66 will be moved inwardly part way towardtheir innermost position. If it is assumed thatthe throttle is now opena certain amount, the speed of the engine will consequently increase,the centrifugal force exerted on weights 66 Will be correspondinglyincreased, and clutch |2 will be applied with acorresponding pressure.

As the engine speed and. this pressure increase together, the point willbereached where the pressure will be sufiicient to prevent furtherincrease in engine speed; If the throttle is held in this position, theclutch will continue to slip at a constant engine speed until'thevehicleis movingfast enough so thatthe driven member clutch |2 willfinally be turning the same speed as the engine and the clutch slippagewill then cease. The speed of the engine then further increases and theforce exerted by the weights 66 eventually becomes great enough so thatthe pistons 45 are forced to the right'by the action of the levers 62,and the weights 66 assume their outermost'position against the rim ofthe fly- 'itial engagement.

wheel as a stop. It will thus :be seen that the oil pressure against thepistons 45 acts as ia"yieldable cushion member not only to preventexcessive forces being exerted at high engine speeds by the centrifugalforce uponthe weights 6B and thereby damaging the mechanisnn-but the oilpressure on the pistons 45 serves to place an upper limit upon thepressure which :can at any time be applied to-clutch l2.

It is to be noted that throughout the range of engine speeds at whichslipping occurs, the clutch pressure is controlled by the centrifugalweights 56, while the rate at which the pressure builds up to "thisamount is, howevencontrolled hydraulically by the action of the pistons45. Experience with centrifugal clutch actuating means has proven themtobe a very satisfactory means very sudden and causes an objectionablebacklash noise or a bumping jerkTin the driving parts between the clutchand the whe'els of the vehicle. Hydraulic means on the'other-handprovides a very smooth" method of obtai'ning in- Therefore, thearrangement above described provides the combined advantages of bothhydraulic and centrifugal'controls.

A sudden initial engagement of centrifugal ciutch, as above referred to,is caused by the fact that as the centrifugal weights move outwardly,the centrifugal force increases due to the increase in the radialdistance to which the weights are moved from the axis of rotation.Therefore, as soon as the weights begin to move outwardly, even thoughtheir speed of rotation may not change, the weights are caused to movesuddenly from their inner to their outermost position. The method ofmounting the centrifugal levers 64, as herein described and shown,completely eliminates this tendency towards sudden action of the weightsbecause as the weights 6'6 swing outwardly and the arcuate portions ofthe levers 63 move or roll upon their points of support upon theflexible strip 68, the effective lever or moment arm of each of thelevers 64 is automatically reduced by an amount sufficient to compensatefor the above describedincrease-Iinthe centrifugal force due to theincrease in the radial "distance of the weights from the axis ofrotation.

Fluid pressure pumps therefore driven at all times through the centraldriven clutch plate 33 at engine speed. The pump it is the main pumpprimarily employed for supplying oil under pressure to actuate thesynchronizer and the clutches ,il'and l2. Due to the fact that thispump. is engine driven, it will not be operative to supplyfluid underpressure if for any reason the engine cannot be started, therefore, itwould not function to supply oil under pressure to the fluid pressureactuated devices by pushing or towing thevvehicle. In order to providefor such a contingency, the rear pump H is provided, which drivendirectly by the outputshaft 2!. The pumpiil also furnishes a sourceofioilior lubricating the variousbearings on the output shaft 2] throughthe "conduit 1 I-a and branch conduits i Pb andcountershaft The enginedriven pump 16.

.14 sleeve 11 and countershaft Speed governor V Mounted upon the outputshaftv 2i within-the housing C is a centrifugal governonindicatedgenerally by the reference character G. governor'comprisesa fixed spider12 keyed as by the key 1-3 to the output shaft 21 and held againstlongitudinal movement relative to said shaft by means of a snap ring T4.vA second spider is also mounted upon output shaft 2-! for slidablelongitudinal movement thereon. Pivotally connected to suitableprojecting bosses T2-aand iii-a of the spiders 12 and 15. respectively,are the ends oflinks 16, I'L -which are pivotally connected at theirother ends-by pins 1-8 upon-which arealso carried the governor weights79. The spiders 72, 15 are normally urged away from each'other by meansof. the

, in Fig. l of the'drawings.

:nism presently to be-described.

Automatic control system :In accordance with the the present invention,the various speed gear ratios, which aremade effective at any instant inaccordance with operating conditions, are primarily under the control ofthe automatic control system, consisting of a plurality of valves andlevers. This system, illustrated in the diagrammatic view of Fig. 2 ofthe drawings, includes a pressure control valve for regulating the oilpressure delivered to the clutch operating pistons 45, 46; a clutchvalve 86 for governing the flow of fluid to apply and release thepistons-4t forthe clutch 1 I; asynchronizer valve 81 for controlling theflow of fluid under pressure to a synchronizer piston 88; pilot valves89 and 90, which are adapted to be operated under the combined influenceof throttle opening as governed by the amount of depression or theposition of the accelerator pedal I 00 and the position of the speedgovernor to cause the clutch valve 85 and the synchronizer valve 81 tooperate at-the-proper time. The system further includes a fluid pressure'operated plunger 9! for momentarily closing the throttle wheneveran upshift is made by means of the'synchronizer piston 88 and an.

interlock valve '92, which permits the throttle to reopen after theupshift is completed.

Accumulator All of the valve members which comprisethe automatic controlsystem are shown in Fig. 2' of the drawingsin a position which theyoccupy when the engine isat rest. ,As soon as the engine is started, oilunder pressure is delivered by the engine driven pump :to the conduit93' and branch conduit 93-50, conduit 93 leading directly to thesynchronizer valve 81 and branch conduit '93-a to an accumulatorcylinder 94, havingv a piston 95 sli'dably. mounted therein. The piston95 is normally held by a spring 96 towards the left hand positionshownin; the drawings. A conduit 9! connect'sthe cylinder 4 withthesump,98- in whicha supply of oil is maintained for delivery to the pumpsIO, N through the suction conduits 98-11, 98-7). The spring 96 iscalibrated at a strength such as to insure proper operating pressure inthe hydraulic system. When the engine driven pump I is rotated uponstarting of the engine, the oil passing through conduit 93 will beblocked at the upper end of the said conduit by the synchronizer valve,which at this instant is in closed position. Oil flowing through branchconduit 93-41, however, will move piston 95 to the right compressingspring 96 until the pressure rises to the desired predetermined point atwhich time the accumulator piston 95 will have been moved to the right asufficient amount to uncover conduit 91 and thereby permit a portion ofthe oil to flow, or be by-passed, back to the sump 98. While this isoccurring, branch passage 99 and lateral branches 99-a and 99-!) thereofwill be filled with oil under the accumulator pressure.

Pressure control valve If now the accelerator pedal I00 is depressed,

'85 is slidably mounted. Downward motion of the piston I02 iscommunicated by a spring 103 to the pressure control valve 85 causing itto move downwardly until the necked portion 85-?) thereof opens thebranch conduit 99-a, thereby permitting oil to flow around the neckedportion 85-1) of the pressure control valve to the conduit I04 andthence to the clutch pistons 45 for actuating clutch I2 for first andthird gear drive. The fluid which passes around the necked portion 85-12of the pressure control valve to conduit I04 also branches to theconduit I04-a to the lower end of a small plunger I 05 mounted below thepressure control valve 85. The pressure of the fluid upon the plungerI05 tends to raise the pressure control valve 85 and when the pressurein conduit I04, I04a becomes sufiicient to overcome the pressure ofspring I03, the pressure control valve 85 will be raised until conduit99-a is closed and drain I06 leading to the sump is opened, therebycausing the oil to be drained off until the oil pressure dropssufficiently to permit valve 85 to again close the drain I06. However,whenever the oil pressure on the small plunger I05 is less than thepressure on spring I03, valve 85 will move downwardly thereby admittingmore oil. A balance will therefore be established between the forceexerted through the spring I03 and the oil pressure in conduit I04 andconsequently upon the clutch operating piston 45. The clutch operatingpiston 45 is thus applied with a pressure which is controlled by theposition of the accelerator pedal.

The pressure required to be exerted upon the accelerator pedal I00 tooperate the pressure control valve 85 forregulating the clutch pressuredepends upon the size of the small plunger I05 rather than the size ofthe pressure control valve 85. As a result of this construction, it ispossible to make the pressure control valve 95 large enough to provideadequate oil passages; and at the same time to operate it witha verylight pressure on the accelerator pedal. W

r If it is to be assumed that the oil pressure has; now moved the clutchpistons 45 to the end of theirtravel and that the accelerator pedali '16I00 is further depressed so that the engine speed increases, thecentrifugal clutch means hereinbefore described will cause the clutch I2to be engaged and the vehicle to start. As the vehicle starts, thegovernor G will be rotated by the output shaft 2|, thus causing theweights I9 thereof to be moved outwardly and the slidable spider I5thereof to be moved towards the fixed spider I2. This movement of thegovernor is communicated to a pair of differential levers I01, I 08having suitable connections (not shown) to the lever 82 that is slidablyconnected in the groove I5-b of the governor. As, shown in Fig. 2, themovement of the governor spider I5, as the speed of the engineincreases, causes the right hand ends of the two differential levers I01, I08 to be'raised. Differential lever I0I is connected by the valverod 89-a to pilot valve 89, while differential lever I08 is connected bythe valve rod 90-a with the pilot valve 90. As the speed of the vehicleincreases and valve 89 is raised by the action of the governor, oilunder pressure will flow around the necked portion of valve 89 fromconduit 99-'-b to conduit IIO from which it will be delivered to thespace below clutch valve 86, thus raising the clutch valve and placingconduit I04 in communication with conduit II I; the oil under pressureflowing from the accumulator through conduit 99 and branch passage 99-athereof through the pressure control valve to conduit I04 and thence toconduit II I around the necked portion of the clutch valve 86 to permitthe fluid to pass to the clutch pistons 46. Clutch pistons 46 will thenbe moved by the oil pressure towards the left in Fig. 1 of the drawingsto cause clutch II to be engaged; the degree of pressure applied toclutch I I depending upon the position of the accelerator pedal I00. Byproper adjustment of the relationship between the pressure of spring I03of the pressure control valve and the degree of throttle opening asdetermined by the position of the accelerator pedal, the proper degreeof clutch pressure for smooth engagement of clutch II can be obtained atall throttle openings. The quality of such a clutch engagement may befurther improved by regulating the rate at which the oil flows topistons 46 through the jet plunger II2 interposed in conduit III betweenclutch valve 86 and pistons 46.

Clutch II now having been engaged, the vehicle will be driven in secondgear by the rotation of shaft I3, gears 22 and 23, countershaft sleeveI1 and gears I8 and I9. Due to the pro- I vision of the overrunningroller clutch I 6-a in gear I6 by driving the countershaft sleeve H athigher speed through gears 22 and 23, the roller clutch IB-a will bereleased and even though clutch I2 remains engaged, the driving of gearsI5 and IE will be ineffective to exert any driving force, upon theoutput shaft 2|. As the speed of the vehicle increases still further,the pilot valve 90 will be raised by the action of the governor ondifierential lever I08 to establish communication between conduit 99-!)and conduit II3, oil flowing through conduit I I3 to the interlock valve92, and piston plunger 9|, which is adapted when it is raised by the oilpressure flowing through conduit II 3 to engage the end of a bellcranklever Il5. Lever H5 is connected by rod II6 with the accelerator pedalI00, there being a lost motion spring connection H! between rod H6 andthe lever II5. When the accelerator pedal is depressed, force will beapplied through spring II1 to cause lever II5 to be moved in acounter-clockwise direction in Fig. 1 until lever I I5 engages theadjustable stop nuts II8 on rod II9 which is connected with the throttlevalve I through the connectin link I2I, a spring I22 being connected tolink I2I to normally urge the throttle valve I 29 towards closedposition. As will be seen from the foregoing, whenever the pistonplunger 9I is raised by the oil pressure as above described, thebellcrank II5 will be moved in a clockwise direction against the actionof spring II'I, thus moving the upper arm of lever H5 away from the stopnuts H8 and permitting the throttle valve I20 to be closed by springI22.

The oil transmitted through conduit II3, as will be hereinafter morefully described, also flows through branch II3-a to the synchronizervalve 61 and tends to cause the latter to be moved downwardly againstthe pressure of spring 8I-a to permit oil in conduit 93 to flow throughbranch IM-b to move synchronizer piston 88 against springs 88-11 and88-2) to actuate the piston rod I23 to which is secured the fork I24that engages with the synchronizer collar 28.

The synchronizer fork I24 is connectedby means of a valve rod 92-a tothe interlock valve 92. Oil which passes through the interlock valve 92from conduit II3 also flows through the branch conduit I25 to the spaceI26 below the pressure control valve 85 to cause the latter to beraised, thereby to establish communication between conduit I94 and thedrain conduit I06 around the necked portion 85-?) of the pressurecontrol valve to conduitIIiB leading to the sump.

This permits oil to escape through the drain conduit I06 from both setsof clutch pistons 45, 46. Up to this point the oil pressure behindpiston 46 is also transmitted through branch conduit II I-a to theinterlock valve 92 and through conduit III-b to the space below thesynchronizer Valve 81, thus preventing the synchronizer valve from beingmoved downward in spite of the oil pressure transmitted from conduitII3-a to the space I27 above it. As the clutch pressure diminishes, theoil pressure in the space below the synchronizer valve is released andthe synchronizer valve is then pushed downward by the oil pressure inbranch conduit I I3-aagainst the pressure of spring 8I-a until it cutsoff the communication between passage I04-b and the drain I28 andestablishes communication between passage I04-b and conduit 93 leadingto the engine driven pump. Oil pressure from the pump I0 flowing throughconduit 93 to conduit I04-b thus moves piston 88 to the left,compressing the heavy synchronizer spring 88-a and causing the lightersynchronizer spring 88-1) to urge the synchronizer collar 28 to the leftthrough the action of the fork I24. As soon as synchronization iscompleted and the internal gear teeth of thesynchronizer collar 28engage the teeth 22-a of gear 22, direct drive is thereby efiected. Asthe fork I24 moves to the left, as above described, it carries with itthe interlock valve 92, thus cutting oiii communication between conduitsII3 andvalve. is now in communication through branch conduit III-b tothe drain conduit I39, the synchronizer valve 81 remains in its downwardposition after the application of clutch pistons 45, as the interlockvalve 92 prevents oil from passing through conduit I I I-a to conduitIII-b. As both clutches are now engaged and the synchronizer collar 28is in engagement with the jaw teeth 22-a of gear 22, the transmission isindirect drive.

As I have found a tendency on the part of the piston plunger 9| to hunt,the fOllOWil'lg-COH- struction of the pilot valve 90 has been employedto correct this-tendency. Slidably mounted upon valve rod Sil-a is aspool-shaped sleeve 90-1). A lateral opening or secondary port 90-0 insaid spool communicates with a clearance space 90-12 II3-a and openingconduits I II-a and II3-a to.

drain conduit I30 through a central conduit I34 provided in theinterlock valve. The oil pressure is thus released from plunger pistonSI, thus latter to move downwardly and re-establish communication of theoil supply to the clutch pistons 45 and 46. As the space below thesynchronizer stem 9IJ-a, As valve 90 is moved upwardly by the action ofthe differential lever I08, as the speed of the car increases andconduit I I3 is opened, the oil under pressure'in conduit II3 flows intothe clearance space 99-d through the secondary port 90-0 to the annularspace 90-9, thus causing the valve spool 90-1) to be moved upwardly adistance equal to the clearance spaces provided between collar SIl-g andspool 90-h, thus establishing communication between branch conduit 99-17and conduit I I3 through'the annular port 90-h to; the conduit I I3which leads to the clutch operating pistons. This action of valve 90occurs with a flip or snap and takesplace without any additional motionof the speed governor, and thereby insures a supply of fluid to thethrottle operating plunger piston 90 that prevents the tendencyofsuch-piston to hunt. It will be noted that'when' the valve 90 movesdownwardly to close communication to conduit I I3, the reverse actionwill take place, the spring 90- causing the valve spool 90-2) to flipdownwardly to its lowermost position,

When the car is stationary and the accelerator pedal is released, it isessential that there'be no I2." Therefore, when the accelerator pedalI09 is in pressure on either of the clutches II 'or its releasedposition, the pressure control valve is urged upwardly by release springI35 to open drain I06. It has been found undesirable to permit this tooccur in direct drive, for as the engine would slowdown, the car wouldcoast in acondition similar to free wheeling whenever the acceleratorpedal was completely released. Better control of the vehicle is obtainedby maintaining a light clutch pressure with released; throttle in directdrive. This is accomplished by the oil pressure transmitted, as aboveexplained} to the space I2! above the synchronizer valve 81 whichpressure, in addition to operating the synchronize! valve, alsooperatesthe small plunger I30 and causes the same to beu-rgedoutwardlyuntil the plunger engages the adjustable screw I37 carried by the oneend of the bellcrank or rocker lever I38, pivoted at i39 and the-arm I40 of which lever contacts with the upper end of I the cup-shaped pistonI02 and thereby-serves" tomaintain a light pressure upon the spring I0319 i of the pressure control valve even though the accelerator pedal maybe fully released. I

It is frequently desirable to provide for quicker acceleration, forexample, when passing another vehicle or to obtain a lower gear ratioautomatically when the vehicle is ascending a steep grade. This isaccomplished with the present invention by the provision of adifferential speed lever I49, the right hand end of which is normallyheld against an adjustable stop screw I56 by spring I6I. The left handend of differential lever I49 is connected by means of valve rod II to apilot valve I52 and also is connected by means of a rod I 53 toaccelerator pedal I66. If the right hand end of lever I49 is heldagainst stop I56, as shown, and the accelerator pedal is depressed,pilot valve I52 will be moved downward cutting off the drain I55 andpermitting oil pressure from conduit II3 to enter conduit I56 throughwhich it passes to the space above the clutch valve 86. Oil pressurethus builds up upon the upper end of valve 86 equal to that alreadytransmitted through pilot valve 89 and passage II6 to the lower end ofclutch valve 86. Since the oil pressure therefore is equal upon bothends of valve 86, the spring pressure of spring 86-a on the top ofclutch valve 86 will force the valve downwardly to the position shown inFig. 1 of the drawings. The oil pressure flowing to clutch pistons 46will then be releasedthrough branch conduit III-c, check valve I51 andrelease valve I58. Since the above action results in releasing thepressure upon clutch pistons 46 and clutch II, the drive must now bethrough clutch I2 and third gear will be obtained through shaft I3,gears I5, I6 and gears 23, 22 to jaw teeth 22-a of the latter andsynchronizer collar 28 to the driven shaft 2I.

If such a shift from fourth or direct drive to third gear be made atvery high vehicle speeds, the engine will be forced to run so fast as tobe either dangerous or destructive. For this reason means have beenprovided to prevent such a shift occurring above a predetermined speed,such for example as 65 miles per hour. When this speed is reached, thespeed governor through a small connecting link I66, which connectsdifferential lever I61 to the differential speed lever I49, will causethe right hand end of lever I49 to be raised against the tension ofspring I6I away from stop I56.- When this occurs, the motion imparted tothe left hand end of the speed differential lever I49 by the acceleratorpedal is now insufficient to move valve I52 far enough to cause the gearshift to be made.

The speeds at which the various gear shifts are caused to take placeautomatically depend upon the combined action of the accelerator orengine throttle and the governor, each of which function to position therespective ends of the differential levers I61 and I 68. It will beapparent that for any particular car speed, the right hand or governorcontrol end of the said levers will be stationary. Shifts may then bemade by moving the left hand ends of said levers by the acceleratorpedal. On the other hand, if the accelerator pedal is held stationary,shifts will be made by the action of the speed governor on the righthand ends of said levers as the vehicle speed changes. The greater theextent to which the accelerator pedal is depressed and therefore thethrottle opened, the farther down the left hand ends of the differentiallevers I61, I68 are moved, and consequently the greater the vehiclespeed which will be required to move the governor far enough to cause anupshift to a higher gear ratio. A

similar action occurs regarding downshifts which take place at higherspeeds, the greater the throttle opening. Adjustably secured uponpushrod I6I which leads from the accelerator pedal to the pressurecontrol valve is a pair of stop nuts I62 which are adapted to engagewith one arm I63-a of a rocker lever I63, which is normally held againstan adjustable fixed stop I 64 by spring I54. Rod I53 which is pivotallyconnected to the right hand end of arm I63-a of rocker lever I63 carriesstops I65, I66 for engagement with differential lever I68. A rod similarto the rod I53, but not shown in the drawings, is located immediatelybehindthe rod I53 and carries stops similar to the stops I65, I66 forengagement with the left hand end of differential lever I61. Rod I53also carries a pair of adjustable stop nuts I61 and I68 for engagementwith the differential speed lever I49. Fixed stops I69 and I16 are alsoprovided for engagement with differential lever I68, there being similarfixed stops, not shown, for cooperating with the left hand end ofdifferential lever I61. The fixed stop I16 for lever I68 and itscounterpart for lever I61 determines the maximum speeds which can beattained before upshifts or shifts from a lower to a higher gear ratioare made. Thus, as the car speed increases and the governor raises theright hand ends of differential levers I61, I68, the left hand ends ofsaid levers will move downwardly until they make contact with the stopsI16. Further, upward movement imparted to th right hand ends of thedifferential levers by the governors will raise the valves 89 and 96successively to the position at which they will cause upshifts to takeplace. It is to be noted, however, that the levers I61, I66 can makecontact with the stops I16 only if stops I66 have been caused to movedownward so that they will not interfere with the left hand ends of thedifferential levers I61, I68 by the depression of the accelerator pedal,and lever I63 has likewise been moved by the engagement of the nuts I62with the right hand end I63-a of lever I63. The various adjustable stopsare set at a position such that the condition above described will occuronly at or very near full throttle opening. For closed or part throttleopening conditions, the difierential levers I61, I 66 will make contactwith stops I66, these being in a higher position than stops I16.Therefore, it will not be necessary for the right hand ends ofdifferential levers I61, I68 to rise as far in order to bring valves 89and 96 to the position at which shifts occur.

Downshifts are similarly influenced by the combination of the fixedstops I69 and the stops I65, stops I65 being movable by the acceleratorpedal. As the car 'speed decreases and as the speed governor moves theright hand ends of levers I61, I'66downwardly, their left hand ends willrise until they make contact with stops I69. As the governor continuesto lower the right hand ends of the differential levers I61, I68, valves69, 96 will successively be brought to the position where they causedownshifts to second gear and then to first gear to occur. If, however,the accelerator pedal I66 is depressed and through the action of stopsI62, lever I63 and rod I53, the stops I65 aremoved downward to suchaposition that the differential levers I61, I68 make contact with thestops I65 rather than with stops I69, it will obviously not require asmuch downward movement of the right hand ends of differential leversI61,

I 68 to move valves 89, 96 to a positionat which,

aware? downshifts will be effected. Therefore, such downshifts willoccur at higher speeds.

Shifts made when levers I01, I88 are in con-v tact with the fixed stopsI69 and H will always occur at the same speed, as such shifts areinfluenced only by the action of the governors G, which are driven inaccordance with the speed of the vehicle, while shifts which occur whenthe levers I81, I98 are in contact with movable stops I65, I68 occur atspeeds determined by combinations of vehicle speed and throttle opening.The various stops are made adjustable so that the positions of the fixedstops and the movable, stops as well as the distances between them canbe varied to produce different effects. If, for example, the distancebetween stops I and I66 is large in comparison to the distance betweenstops I69 and I18, the shifts will be influenced by throttle openingonly at or near the ends of the motion of the accelerator pedal I60,thus the throttle opening can be varied throughout a wide range withoutcausing the automatic gear changing mechanism to function. This has beenfound desirable under some driving conditions. I For example, whenascending a very long gradein a lower gear ratio, it is convenient toregulate the speed of the vehicle by motion of the throttle within itsmiddle range without the need of causingv unnecessary gear shifts whichwould be come annoying if they occurred too frequently. Anothercondition where this feature is desirable is when accelerating a car in,second gear on a level road. Many drivers prefer to bring the speed ofthe vehicle up to the speed at which they intend to proceed byaccelerating entirely in second gear. Then upon'releasing the throttleor raising the foot oil the accelerator pedal, the shift into directdrive can be made. This is particularly desirable with the type oftransmission gear arrangement shown in Fig. 1 wherein it isnecessary forthe engine power to be interruptedby either a manual or an automatic,closing of the throttle so that the synchronizer collar 28 may beengaged with the jaw teeth 22-a of the gear 22. With'the acceleratorpedal I00 in closed throttle position, the lever I63 is held againststop I84 by spring I54";v In this position there is a con-- siderableclearance between lever I63 and stops I62 50 that an initial downwardmovement of the accelerator pedal I88 does not produce any move-- mentof lever I63 and its associated stops to effect the gear shifts. motionis useful to insure that the pressure control valve 85 will becompletely released whenever the operators foot is removed from theaccelerator pedal I88. A certain amount of throt tle opening isobviously necessary to bring the vehicle to any of the speeds at whichthe sh1fts should occur. Due, however, to the above-mentioned lostmotion, this slight amount of throttleopening does not effect theshifting speeds.

Let it be assumed now that the 'vehicle is driven up a steep grade inthrottle wide-open and that the grade is such as to cause the vehicle tocontinue to slowdown until the governor through the action of the abovedescribed stops and'levers moves valve 98 to the position at which itopens conduit I I3: and permits the oil' to drain therefrom. Thisrelieves the pressure inthe space I'Z'I above the synchronizer valve 81whereupon the said; valve is moved upward bythe pressure of the springB'I-d, thereby opening conduit IM-b to the-01 E113 I28 or movingsynchronizer valve 81 to theposie tion shown in Fig. 2 of the drawings.

This idle travel or lost.

third gear with the This re-.

sults in relieving the oil pressure. from the right hand end ofsynchronizer piston 88. The heavy spring SS-a will therefore urge thesynchronizer piston 8-8'and fork I24 to the right, the force of thespring 88-a being exerted upon washer I'M,- and enlarged head I'I5 ofshift rod I23 to which the synchronizer shift fork I24 is attached.

Since, under the conditions now assumed, the throttleis open and theenginepower was being transmitted through jaw teeth 22-a of gear 22 tothe internal gear teeth ZB-a of the synchronizer collar 28, there willbe a heavy load on these teeth and consequently they will not slideapart or disengage readily under the influence of the shift fork I24.Therefore, ignition interrupting devices are supplied. These consist inmaking the end of the synchronizer fork I24 which engages with the.synchronizer collar 28 slightly narrower than the annular groove in saidcollar 28. This permits the synchronizer shift fork .124 to move a shortdistance without imparting its. motion to collar 28. A small projectionI'II' provided on the right hand end of the hub or boss of the shiftfork I24 but which, as the synchronizer collar in the condition assumedhas been slid to the left, is also in its extreme left hand position,will make contact with and raise the short rod I18 in the initialmovement of the shift. fork I24 to the right. Rod I18 will move themovable spring electrical contact Il s away from the fixed electricalcontact I89. The contacts I19 and ISO are so interposed in the ignitioncircuit that when they are separated a momentary interruption in thepower of the engine occurs so that the load upon the-jaw teeth 22a of'gear 22 and the internal gear teeth 28-a of the synchro nizer collar 28is momentarily released. Consequently, synchronizer collar 28 may bedisengaged from the jaw teeth 2'2-a by the pressure of the spring 88-11acting upon synchronizer fork I24. As soon as the projection I'I'fpasses beyond rod I-IB, electrical contact between the contact membersI19, I86 is again re-established and the engine power is resumed.

Since the vehicle was assumed to be in third gear with throttle wideopen, valve I52 is in itsv downward position to cause oil to betransmitted through'passage it to hold the clutch valve 86 in itsdownward or clutch releasing: position, as

shown in'Fig. 2 of the drawings. Clutch pistons 48 and clutch .II weretherefore released. As

soon as pilot valve 33 moved downward. to ,re-

moved upward by the oil pressure below the valvett in the conduit H8. Asclutch valve moves upwardly, it cuts on the drain through conduit I58i-aand releases valve I58 and admits oilfromconduit H34- around the neckedportion of clutch valve 88 to conduit I II and jet plunger [I2v tore-apply clutch pistons 4 8 and clutch II. Second gear drive istherefore effected through clutch'II, shaft I3, gears I5, l6,countershaft sleeve I1, gears I8, I3 and roller clutch 20 to outputshaft 2I.- The above described sequen'ce'of operations is also utilizedto make a gear shift from fourth or direct drive to second gear drive.This occurs if the throttle is opened when the vehicle is running slowlyin fourth gear. In this case the sequence-of operationsis the same,'asabove described, except that the valve I52 is in the upper position, asshown in Fig. 2 ofthe drawings, and the clutch valve 86 is alsoin itsupper position so that clutch pistons 46-and 23 clutch II are alreadyengaged before the shift occurs.

If, after shifting down into second gear, the grade is so steep that thevehicle speed still decreases, a speed Will eventually be reached wherethe pilot valve 89 will have been moved downward so as to permit the oilto drain from conduit IIO, thereby releasing the pressure below clutchvalve 80 and permitting it to be forced by the pressure of spring 86-ato the lower position shown in Fig. 2. This permits the oil to drainfrom clutch pistons 46 to passages III and III-c through check valve I51and release valve I58. Clutch II is therefore released and since clutchI2 is still engaged, the drive will be taken up by it through sleeve I4, gears I5 and I6, roller clutch IG-a and gears I9 and I 9 throughroller clutch 29 to output shaft 2I, and the vehicle is now in firstgear.

Should it be desired to shift from direct drive into second gear inorder to obtain extreme acceleration at a speed above that at which itwould occur automatically, as hereinbefore described, the manual shiftrod I90 is moved by manual means until its enlarged end I9I makescontact with the synchronizer shift fork I24; When this occurs, a camI92 secured to the right hand end of the manual shift rod I90 engagesthe left hand arm I63-b of lever rocker lever I 63 causing the lever tofulcrum about its pivotal mounting and causing the right hand end I63-athereof to move downward sufiiciently so that stop I05 upon rod I53makes contact with the left hand end of differential lever I08, thusmoving pilot valve 90 downwardly to the position where, as previouslydescribed, it will cause a downshift into second gear by establishingthe fluid pressure connections to produce a sliding of the synchronizercollar 28 to the right out of mesh with the jaw teeth 22-11 of thesynchronizer 22. It is to be noted here that this is a free wheelingsecond gear drive since it is trans-v mitted through the roller clutch20 and it is therefore not adapted for using the engine as a brake. Ifit should be desired to establish a positive connection between theengine and the output shaft 2| through the second gear ratio so as toemploy the engine as a brake, this can be accomplished by releasing theaccelerator pedal I00 and then by further movement of the rod I90 to theright, shifting synchronizer gear fork I24 and the synchronizer collar28 manually to the right to cause the internal gear teeth thereof tomesh with the jaw gear teeth I 9-a of the gear I9. When the synchronizergear shift fork I24 is so moved to the right for the above describedoperation, piston 88 must of necessity move with it. During this motionof the fork I 24' and piston 88, washer I14 and the washer I93 movetogether as a unit and there is no spring pressure of the springs Bil-aand 8 8-!) to be overcome. A snap ring I94 which limits the movement ofwasher I93 towards the left remains in fixed position during this abovedescribed movement of the piston 80 under the manual operation of themanual shift rod I90, as above described.

Since there is no pressure in space I21 above the synchronizer valve atthis time, the plunger I35 and lever I38 will not maintain any pressureupon the cup-shaped plunger I02, and the pressure control valve 85 istherefore free to be released if the accelerator pedal I00 isnot'depressed and the throttle would therefore be closed as wouldnaturally be the case when using the engine as a brake. The right handend of the manual shift rod I90 is therefore adapted to engage anadjustment screw I95 secured within an upwardly projecting arm I40-a ofthe lever I38-I i0, thereby causing lever I40 to be pressed downwardlyupon the cup-shaped plunger I02 and thereby maintain enough clutchpressure through pressure control Valve to drive the engine.

In the event the engine will not start by the usual starting means andit is desired to start the engine by pushing or towing the vehicle, themotion of the vehicle will obviously drive output shaft upon which ismounted the rotor of vehicle driven pump II. Oil from this pump willthen pass through check valve I96 to conduits 93 and 93-11, which arenormally filled with fluid delivered by the engine driven pump 10. Themanual shift rod I99 is then placed in the same position as for secondgear braking and so as to engage the synchronizer collar 28 with the jawteeth I9a of gear I9. As the vehicle speed increases and the governorraises the right hand end of differential lever I01, pilot valve 89 willrise to the point at which it admits pressure from conduit 99-h toconduit IIO, thus raising clutch valve 90 and admitting oil throughpassage III to apply the clutch pistons 46 and clutch II. Since themanual shift rod I90 through stop I and levers HID-a, I 40 holds thepressure control valve 85 downward, there will be sufficient clutchpressure so that the motion of the car will start the engine.

As it is desirable to cause the clutch pressure to increase as soon asthe vehicle begins to move, there is incorporated in the small pressurecontrol valve plunger I05 mounted below the pressure control valve 85means for increasing the clutch pressure as soon as the vehicle beginsto move. When the vehicle driven pump II is driven by the vehiclethrough rotation of the output shaft 2|, it causes pressure to build upin conduit I91 connected to the output of the vehicle driven pump belowthe check valve I96. This oil under pressure passes to the space I98above the enlarged head provided on the lower end of the small plunger I05 and thereby causes a downward force to be exerted upon plunger I05.Accordingly, a greater pressure will now be required below plunger I05in branch conduit I04-a of conduit I04, and also upon clutch pistons 45to balance the pressure of spring I03 of the pressure control valve, andas a result, the clutch pressure will have been increased by the motionof the vehicle even though the accelerator pedal I00 has been held in afixed or closed throttle position. The above described feature would beof particular advantage if the present transmission were to be usedwithout the aid of the centrifugal devices for assisting in theregulation of the pressure upon clutch I2, such as would be the case forexample if the pivotal point 64 for the levers 62 were a fixed pivot andthe clutch pressure pistons 45 were permitted to make a sufiicientstroke to engage clutch I2 without the aid of the centrifugal weights 60and levers 64. If such were the case, the provision of conduit I91leading to the space I98 above the enlarged head of plunger I05 wouldhave two marked advantages, as it would be possible to adjust thelinkage connecting .the accelerator pedal with the throttle and with thepressure control valve so that when the car is stationary, aconsiderable amount of clutch slipping would occur to produce a smoothand very gradual start. As soon as,-however, the car however, notsufficient for effective shifting as itresults in a prolonged andunpleasant amount of clutch slipping during the shift. The devices abovedescribed make it possible to obtain the best degree of clutch pressurefor both starting and. for gear shifting.

As will be seen from the foregoing description,'

clutch II is applied lay-clutch pistons 46 when shifting from first tosecond gear, when shifting from second to fourth gear, and also whenshifting from third to fourth gear. Since in the case of shifting fromfirst to second'gear, the vehicle speed is relatively low and the torqueapplied to the output shaft is relatively high as compared to the lattercases of shifting from second or third to fourth gear drives, arelatively more gradual application of clutch pressure is desirable inthe first case than in the latter cases in order to effect smooth shiftsas promptly as possible. In order to secure the desired clutchapplication rate for each case, the jet plunger H2 is provided. When thevehicle is traveling in first gear, there will be no fluid pressurebehind the synchronizer piston 88 and the spring 2-0 will therefore holdthe jet plunger in the raised position shown in the drawings, and theoil passing through conduit III must, therefore, fiow through the smallorifice II2-a in plunger IIZ. When the synchronizer collar 28 is movedto the left for third or fourth gear drive, there is' oil pressurebehind piston 88 and this pressure will push the jet plunger I I2downwardly moving the larger hole IIZ-b into alignment with conduit III.When the smaller hole I I2-a is aligned With conduit III, the rate offlow of oil under pressure to the clutch-pistons 46 will therefore bemuch slower and the clutch pistons 48 Will therefore cause the clutch IIto be more slowly and gradually applied, Whereas in. efiecting fourthgear drive at the higher speeds, when the orifice II 2-1) is inalignment with conduit 7 I I I, the oil will flow much more quickly tothe clutch pistons 48 and cause clutch I I to be more quickly applied.

Although it is desirable to admit the oil to the pistons 48 graduallyfor smooth and gradual application of the clutch I I, it is imperativethat it be possible to release the said clutch pistons at a more rapidrate to make a downshift from fourth gear to third gear promptly upondepressing the accelerator pedal I86. In order to accomplish thispurpose,v check valve I5! is provided .in branch conduit I I Ic in orderto by-pass thejet plunger II2. As will be obvious from an inspection ofthe drawings, when pressure is released in conduit II I to permit theclutch pistons 48 to travel to the right, the oil pressure will movecheck valve I51 off its seat and thus permit the oil to flow morerapidly through conduit IiI c and by-pass around the jet plunger H2. 1 I

In making downshifts from fourth gear to third gear, and especially fromsecond gear to first gear with open throttle by releasing clutch pistons45 and clutch I I, the engine power is applied suddenly through rollerclutch Iii-a, thus tending to cause a sudden jerk which is unpleasant 26and objectionable. In order to smooth outthis jerk, the release valveI58 has been added. It consists of a disk ISB-b normally held upon itsseat by a light spring I58-c. When the clutch valve 86 is operated torelease oil from the pistons 46 through valve I58, the pressure of theoil escaping will at first move the valve I58 off its seat against thepressure of spring I58-c, the clutch II will then begin to slip and asit slips, the engine speed will increase until the engine and clutch I2v are turning fast enough so that the overrunning clutch- IIi-a willbegin to take a part of the load. When the oil pressure has been reducedan amount'equal'to the force ofspring I58-c, the disk 'I58- b againrests against its seat 7 and the oil continues to escape through a smallhole in valve I58 until the remaining pressure is slowly removed fromclutch II and the load-has now been transferred gradually from clutch IIto clutch I2. 7

To summarize the operation of the transmission and automatic controlthereof: Beginning with the vehicle at rest, the engine is startedcausing the engine driven pump 18 to deliver oil under the accumulatorpressure to the conduit as and conduit 98 with its branches 99-11, 8947.When the operator depresses the accelerator I08, the main or pressurecontrol valve 85 is opened, thereby permitting fluid to flow fromconduit BS-a through conduit I34 to the clutch pistons 55, therebycausing clutch I2 to be engaged under combined effect of centrifugalforce and fluid pressure to establish first gear drive. As the cargainsspeed infirst drive, the governor G raises the right hand ends ofdifferential levers I131, HES and when pilot valve 89 is raisedsufiiciently to establish communication between conduit H8 and conduit99-h, fluid under pressure flows through conduit II 8 to the lower endof clutch valve 86 raising it and permitting the fluid which has beenadmitted to conduit I04 by the 7 pressure control valve to flow acrossalso to conduit III' to clutch pistons 46 which apply clutch II. Clutch-II then takes over the drive in second gear while clutch I2 remains inengagement; the overrunning clutch Iii-a ingear I6 releasingautomatically and permittin the gears 22, 23 to take over the drive. Thefluid admitted to conduit HI also flows through conduit III-a across theinterlock valve 92 to conduit III-b and'through the latter to the bottomof synchronizer valve 81; but has no immediate effect there on. As thespeed of the car increases and the right hand end of differential leverI88 is raised sufficiently, pilot valve 98 is opened and fluid flowsthrough conduit IIS'to interlock valve 92 and simultaneously throughconduit I I3-a to the top of syn'chronizer valve 81. The fluid whichpasses through the interlock valve 9-2 flows throughconduit II8-b andraises piston plunger 9i to momentarily permit the throttle valve I28 tocloscQsaid fluidalso flows through conduit I25 to the space I26 belowthe main control valve 85 raising it and opening drain I86, thusrelieving the fluid pressure in both conduits I84 and III and'thusreleasing clutches I2 and II.

The release of the pressure in conduit III and concomitantly in conduitsIll-a and III-b now .ermits'the fluid pressure in II3-a to move thesynchronizer valve 3'! to close drain I28 and open the supply conduit 53to conduit IM-b, thus permitting the fluid pressure to be exerted onsynchronizer'piston 88 to move it and synchronizer fork I3 2 to the leftand slide synhronizer collar 28 into engagement with gear 22,'therebycoupling input shaft I3- of the transmission in direct drivingengagement with the output the clutchpistons 45 and 45 and drivingengagement-of the clutches II and I2, hence the-car proceeds in directdrive through clutch I2,.shaft I3 and the direct coupling of the latterthrough the synchronizer collar 28 to the output shaft 2 I. With bothclutches II and I2 engaged and direct drive coupled, gears I and I6 areineffective-because gear 23 will'be drivin the countershaft sleeve I? ata higher speed than gear I6 is rotating thereby releasing roller clutchI6-a. Third gear is made effective, as hereinbefore described, wheneverthe operator with the car in direct :drive depresses the accelerator toan extentsuflficient to cause the valve I52 to be opened, therebyadmitting fluid under pressure to the top of clutch valve 81 to depressit and cut off the communication between conduits I04 and II I, thusrelieving the pressure on clutch I I and making direct drive throughshaft I3 ineffective While'leaving the pressure through conduit IM-toclutch I2 uninterrupted so that, although the drive through the directcoupling of the synchronizer collar 28 to the gear 22 is not disturbed,it is now effective through the sleeve I4 and the gear reduction of thegears I 5, I 6 and gears 23, 22. It will be seen from the foregoing thatunder normal driving conditions and during the major period of operationof a vehicle equipped with a-transmission'constructed in accordance withthe present invention, the synchronizer sleeve 28 Willremain shifted tothe left (Fig. 1) to couple gear-'22 to the output shaft'ZI of thetransmission to establish direct drive with both clutches II and -I2 inengagement; third gear being established, as above described, by theoperator depressing theaccelerator pedal I00 to cause the pilot valve152 for the third gear clutch to be depress ed,-thus interrupting theflow of fluid to the clutch pistons 16 for clutch II. Should the speedof the car decrease, as a result of the driver raising his foot on theaccelerator pedal thereby pe rrnitting the pressure control valve 85 torisg and. as the pilot valves 89 and 90 will drop due to the action ofgovernor weights 13, the flow of fluid through conduit 3' to thesynchronizer interlock valve 92 will be interrupted by the lowering ofpilot valve 90. As the pressure control valve 85 rises, it will cut offthe flow of ..fluid through conduits I04 and III to both sets of clutchpistons 55 and M5. The release of the pressure in conduit II3 by thelowering of the pilot valve 99 relieves the pressure on the top of thesynchronizer valve 87 and cuts off the flow of fluid to the.synchronizer piston 88, thus permitting the springs 88-a and 88-1) tomove the synchronizer piston to the right, thereby carrying thesynchronizer fork 24 and synchronizer collar 28 back to the neutralposition, as shown in Fig. 2 of the drawings. The movement of the.synchronizer fork and collar 28back to neutral positionalso moves theinterlock valve to the position shown in Fig. 2, in which position the.inter-lock valve againestablishes communication between conduits H3 andlI3-b, and all of the valves occupy the positions in which they areshown'in Fig. 2. First gear drive will then be re-established by theoperator depressing the pedal to first move the pressure control valvedown and re-establish first gear drive, as hereinbefore described;second gear drive being reestablished as the vehicle again regains speedand causes the governor to open pilot valve 89 and re-establish secondgear drive.

It will be noted that when the car is accelerating, the synchronizerpiston 88 will not be moved to shift the synchronizer collar 28 as longas fluid under pressure is being delivered through conduit III to theclutch piston 46.

The modification Of the automatic fluid pressure transmission shown inFigs. 9' and 10 is generally similar in operation. to the transmissiondescribed above but includes a number of important differences inconstruction and operation." With regard to the'transmission proper, themost important constructional modifications include the following:' Asolid gear 300 is rotatably journaled on the output shaft 3! by means ofa sleeve bearing 3il2,'instead of the overriding clutch typeiof gear I9keyed to the output shaft as shown in Fig. 1: 'The synchronizer collar303-a is normally held by spring means in an extreme righthand positionso as to engage the jaw teeth 304 of the gear 300, instead of ma neutralposition, and first and second'gear drives are thus effected through thesynchronizer unit 383 which is keyed to the output shaft 30 I. First andthird gear clutch member 385 is engaged by means of fluid pressurewithin a diaphragm 3&6 moving pressure plate'iifll through a plate 303associated with the diaphragm member 306, and in a similar manner secondand fourth gear clutch member 309 is engaged by fluid pressureintroduced into a diaphragm SIG which transmits movement to pressureplate 3 by means of plate 3| 2 and bolts 3I 3, instead of by the pistonand'lever arrangement shown in. Fig. l. The influence of engine speed ineffecting engagement of the first and third gear clutch is accomplishedthrough the use of a centrifugal valve 3M held with a pressureproportional to the speed of the engine in closing position over anexhaust port 3I5 associated with the diaphragm 306, instead of by theWeight and lever means shown in Fig. 1.

With respect to the modified fluid pressure control system shownin Fig.10, the principal differences include cam means for transmitting motionfrom the accelerator to the throttle, main pressure control valve andfloating levers; a different arrangement for effecting manual secondgear drive; a different type of interlock valve; an additional timingvalve; and additional relay and quick release valves.

The'construction and operation of the modifled control system andtransmission proper may readily be seen by briefly following throughsuch operation under typical driving conditions.

When the engine is started the engine driven pumpfi I6 introduces fluidunder pressure to main and'branch supply conduits 3!! and M8. When apredetermined pressureis reached, for example eighty pounds per squareinch, the by-pass valve 3E9 is moved to the left admitting fluid toconduit 320 which leads to the first and third gear clutch diaphragm305, schematically shown in Fig. 10 as a piston for purposes ofconvenience. Such fluid initially escapes through the exhaust portassociated with the centrifugal valve 3M since 'such'valve is lightlyheld in closing position by the relatively slow speed of the idling therelay valve 32! to the 29 motor. Suchfluid may alsoescape b y movingspring pressure of spring 322, thereby uncovering an exhaust conduit323.

When the accelerator is depressed, rod 324 is moved to the rightrotating the cam member 325 in a clockwise direction, thereby causingone of the cam faces 323 to open the throttle 32? through actuation ofthe bellcrank member 323 which compresses the spring 323 moving rod 333and throttle lever 33! against the tension of spring 332. The othercamface 333 simultaneously moves rod 334 to the right rotating thebellcrank arm 335, thereby depressing the pres sure control valve 333through compression spring 33'! and admitting fluid under pressure fromsupply conduit 3V! to conduit 338. Such fluid passing intobranchflconduit 339 actuates plunger 340 closing the pressure controlvalve 338 when the pressure of the fluid admitted to conduit 338balances the force of compression spring 331, thereby permitting theamount of pressureadmitted to conduit 338 to be controlled by the extentof accelerator depression. The fluid pressure in conduit 338 assists therelay spring 322 inmoving the relay valve 32! to the left closing offexhaust conduit 323 and the increased engine speed resulting from theopening of the throttle causes the centrifugal valve 3m to block withgreater force the flow of fluid through such valve. The combined efiectof closing the exhaust conduits associatedwith the relay and centrifugalvalves builds up pressure in conduit 320 and the first and third gearclutch diaphragm 306. The pressure available to actuate such diaphragmis limited, for example to 85 pounds per square inch, by the safetyvalve 335 communicating with an exhaust port 342.

The manner in which fluid is admitted from conduit 323 to the first andthirdgear clutch diaphragm 336 and the 'operation'of the centriiugalvalve 3! may be more clearly seen from a detailed examination of Fig. 9.The dia phragms 33B and 3) are seated in a diaphragm plate 343 havingahub 343 piloted to first and third gear sleeve 335 upon bearings 3 33and 3M. Sleeve 335 is in turn supported in its right hand end by theball bearing 338. The diaphragm plate 343 is connected to and driven bythe central driving plate 333 through a plurality of circumferentiallyspaced bolts 353 and through clutch cover 35% riveted to the diaphragmplate 343 as at 352. The rotating hub 334 of the diaphragm plate 343 isprovided, with annular grooves 353 and 353 androtates within acylindrical bore 355 in a stationary housing 353. These grooves areseparated and sealed by piston rings 35?. A longitudinal duct 358communicating with the annular groove 3E3transmits oil under pressure todiaphragm 333; phragm communicates with the exhaust port 3 andcentrifugal valve 3M which are located in the diaphragm plate 333. Asimilar duct 353 leads from annular groove ,.53 to the diaphragm 3!!!for actuating second and fourth gear clutch 303. It will be notedthatthe centrifugal valve 3M is associated only with the diaphragm 30.53for the first and third gear clutch, the pressure in the diaphragm 3!for second and fourth gear clutch being governed by the combined effectof throttle position and vehicle speed as hereinafter more fullydescribed.

In a manner similar to the transmission shown in Fig. l, the first andthird gear clutch trans mitsfirst gear drive through sleeve 34-3 togear- This dia right against the light force of the relay valve initialresistance of '30 360, overriding gear 36!, countershaft 332, longitudinally shiftable gear 363, solid gear 303, jaw teeth 304,synchronizer collar -303-a, and synchronizer unit 303 to the outputshaft 30!.

It is to be noted that the pressure of engage: ment of the first andthird gear clutch 305 is determined by the lower resistance of thecentrifugal valve 3M or the relay valve 32! to the escape of fluiddelivered under pressure to conduit .320. When the engine is idling atnormal idling speed with the accelerator released, neither thecentrifugal valve 3M nor the relay valve 32! offer'suflicient resistanceto permit the pressure in diaphragm 306 to overcome the clutch releasealways be effective to prevent clutch application while the acceleratoris released. If the accelerat-or is fully depressed to wide openthrottle position, the pressure control. valvev 333 will admit the fullpres-sure in conduit 3!! into conduit 338 and the relay valve 32! willthus offer ares'ista'n'ce equal to such pressure plus. the effectivelight pressure of spring 322. This will far exceed the the centrifugalvalve 3! which latter valve will thus control'the clutch engagementpressure-during acceleration in first gear. Under Wide open throttle theengine will accelerate rapidly and when it reaches'a predeterminedspeed, c. g.,600 R. P. M., thepressure in diaphragm 306 will overcomethe'clutch release spring and the clutch 305 will begin to-drive thevehicle. As the engine continues to accelerate, the clutch applicationpressureis increased in accordance with engine speed, positive drivebeing established as soon as the sleeve .345 reaches the speed of theengine. At an engine speed above that at which positive drive isnormallyestablished, e. g., 1,200 RJR'NL, the resistive force of the'centrifugalvalve 3M becomes greater than that of relay valve 32! and" the clutchapplication pressure is thereafter limited by the relay valve 32!,together with'thesafety valve 34!. In starting the vehicle with theaccelerator de-" pressed to intermediate positions,the resistive 3'2 islikewise A normally somewhat greater than that of the centrifugal valve323 until somewhat after positive drive is established so thatfirst/gear clutch application pressure normally is a function of enginespeed whether acceleration takes place under full,'intermedi-ate, orgradually increasing throttle opening. r The second gear drive iseffected when the clutch pilot valve 334 is' depressed under the combined influence of accelerator position and vehi cle speed, to behereinafter more fully described, to a position where fluid-pressure inconduit 3!! and branch conduit 335may pass to conduit 353 gears 314 and313 and countershaft 332', 1 longitudinally shiftabl gear

